Inflammatory disorder of unknown cause that primarily affects
the axial skeleton; peripheral joints and extra-articular structures
may also be involved .
AS causes pain, stiffness, disability, decreased spinal mobility,
and decreased quality of life
Disease usually begins in the second or third decade.
HLA-B27 present in > 90% cases
Sacroiliitis is usually one of the earliest manifestations.
Pathogenesis of AS
Incompletely understood, but knowledge increasing
Interaction between HLA-B27 and T-cell response
Increased concentration of T-cells, macrophages, and pro-
Role of TNF
Inflammatory reactions produce hallmarks
In some cases, the disease occurs in these predisposed people
after exposure to bowel or urinary tract infections.
The enthesis, the site of ligamentous attachment to bone, is
thought to be the primary site of pathology.
Enthesitis is associated with prominent edema of the
adjacent bone marrow and is often characterized by erosive
lesions that eventually undergo ossification.
Synovitis follows and may progress to pannus formation
with islands of new bone formation.
The eroded joint margins are gradually replaced by
fibrocartilage regeneration and then by ossification.
Ultimately, the joint may be totally obliterated.
Clinical Features of AS
Skeletal Axial arthritis (eg, sacroiliitis and spondylitis)
Arthritis of ‘girdle joints’ (hips and shoulders)
Peripheral arthritis uncommon
Others: enthesitis, osteoporosis, vertebral,
fractures, spondylodiscitis, pseudoarthrosis
Extraskeletal Acute anterior uveitis
Cauda equina syndrome
Enteric mucosal lesions
Insidious onset dull pain in the lower lumbar or gluteal
Low-back morning stiffness of up to a few hours
duration that improves with activity and returns following
periods of inactivity.
Pain usually becomes persistent and bilateral. Nocturnal
Predominant complaint - Back pain or stiffness.
Bony tenderness may present at - costosternal
junctions, spinous processes, iliac crests, greater
trochanters, ischial tuberosities, tibial tubercles, and
Neck pain and stiffness from involvement of the cervical
spine : late manifestations
Arthritis in the hips and shoulders (“root” joints) : in 25 to 35% of
Arthritis of other peripheral joints: usually asymmetric.
Pain tends to be persistent early in the disease and then
becomes intermittent, with alternating exacerbations and
In a typical severe untreated case- the patient's posture
undergoes characteristic changes, with obliterated lumbar
lordosis, buttock atrophy, and accentuated thoracic
Lumber lateral flexion
TEST and MEASUREMENT for AS
Occiput To Wall Distance ( Flesche Test )
The occiput to wall distance
should be zero
Maintain starting position i.e.
ensure head in neutral
alignment), chin drawn in as
far as possible. Measure
distance between tragus of
the ear and wall on both
sides, using a rigid ruler.
Ensure no cervical
extension, rotation, flexion
or side flexion occurs.
Patient supine, head in
neutral position, forehead
horizontal (if necessary head
on pillow or foam block to
allow this, must be
documented for future
Gravity goniometer / bubble
inclinometer placed centrally
on the forehead. Patient
rotates head as far as
possible, keeping shoulders
still, ensure no neck flexion or
side flexion occurs.
Normal ROM: 70-900
Measured as the difference between maximal
inspiration and maximal forced expiration in the
fourth intercostal space in males or just below the
breasts in females. Normal chest expansion is ≥5
Lumbar flexion (modified Schober)
With the patient standing
upright, place a mark at the
lumbosacral junction (at the
level of the dimples of Venus
on both sides). Further
marks are placed 5 cm
below and 10 cm above.
Measure the distraction of
these two marks when the
patient bends forward as far
as possible, keeping the
knees straight• The distance less than 5
cm is abnormal
Finger to floor distance
Expression of spinal column
mobility when bending over
forward; the dimension that is
measured is the distance
between the tips of the fingers
and the floor when the patient
is bent over forward with knees
and arms fully extended.
Lateral spinal flexion
Patient standing with heels and buttocks touching the wall,
knees straight, outer edges of feet 30 cm apart, feet parallel.
Measure minimal fingertip-to-floor distance in full lateral flexion
and without flexion, extension or rotation of the trunk or
bending the knees.
Greater than 10cm is normal.
Range of motion
Forward flexion: 0 to 45
Extension: 0 to 45 degrees
Left Lateral Flexion: 0 to 45
Right Lateral Flexion: 0 to 45
Left Lateral Rotation: 0 to 80
Right Lateral Rotation: 0 to 80
Forward flexion: 0 to 90
Extension: 0 to 30 degrees
Left Lateral Flexion: 0 to 30
Right Lateral Flexion: 0 to 30
Left Lateral Rotation: 0 to 30
Right Lateral Rotation: 0 to 30
TESTS FOR SACROILITIS
Pelvic compression test
Pump Handle test
stresses the sacroiliac
Increased pain during
this test could be
indicative of joint
PELVIC COMPRESSION TEST
Test irritability by compressing the pelvis with the
patient prone. Sacroiliac pain will be lateralised to
the inflamed joint.
Patrick's test or FABER test
The test is
performed by having
the tested leg flexed,
externally rotated. If
pain results, this is
a positive Patrick's
HLA B27: present in ≈ 90% of patients.
ESR and CRP – often elevated.
Elevated serum IgA levels.
ALP & CPK raised.
Early: blurring of the cortical
margins of the subchondral bone
Followed by erosions and sclerosis.
Progression of the erosions leads to
“pseudo widening” of the joint
As fibrous and then bony ankylosis
supervene, the joints may become
The changes and progression of the
lesions are usually symmetric.
Seen in Ferguson's View
(specialized sacroiliac view).
Dynamic MRI is the procedure of
Loss of lordosis/ straightening
Reactive sclerosis- caused by
osteitis of the anterior corners of
the vertebral bodies with
subsequent erosion (Romanus
lesion), leading to “squaring” of
the vertebral bodies.
Ossification os supraspinous &
interspinous ligaments “ dagger
Formation of marginal
Later Bamboo spine
appearance when ankylosis of
Modified Newyork Criteria (1984) 4 + any of 1/2/3
1. Inflammatory low back pain > 3 months
(Age of onset < 40, Insidious onset, Duration longer than 3
months, Pain worse in the morning, Morning stiffness lasts
longer than 30 minutes, Pain decreases with Exercise, Pain
provoked by prolonged inactivity or lying down, Pain
accompanied with constitutional Symptoms- Anorexia,
Malaise, Low grade fever)
2. Limited motion of lumbar spine in sagittal & frontal planes
3. Limited chest expansion (<2.5cm at 4th ICS)
4. Definite radiologic sacroiliitis
Disease Specific Instruments For The Measurement In
Bath ankylosing spondylitis disease activity index
Bath ankylosing spondylitis functional index (BASFI) Function
Dougados functional index (DFI) Function
Bath ankylosing spondylitis metrology index (BASMI) Function
Modified stoke ankylosing spondylitis spinal score
1. Regular physical therapy
3. Sulfasalazine, in doses of 2 to 3 g/d- Effective for axial and
4. Methotrexate, in doses of 10 to 25 mg/wk- primarily for peripheral
5. Local Corticosteroids injection- for persistent synovitis and
6. Medications to avoid- Long term Systemic Corticosteroids, gold
7. Anti-TNF-α therapy - heralded a revolution in the management of
Infliximab (chimeric human/mouse anti-TNF-α monoclonal
Etanercept (soluble p75 TNF-α receptor–IgG fusion protein)
have shown rapid, profound, and sustained reductions in all
clinical and laboratory measures of disease activity.